Hydraulic system of the E-153 A excavator consists of two control boxes (hydraulic valves), hydraulic power cylinders, an oil tank with a capacity of 200 liters with filters and hydraulic lines with safety valves.
The power source of the hydraulic system with the working fluid is the pumping group.
The pumping group consists of two axial plunger pumps NPA-64 and an increasing cylindrical gearbox, which ensures the rated speed of rotation of the pump shaft - 1530 rpm. Such a rotation speed with a specific pump capacity of 64 cm3 / min provides a supply of 96 l / min of oil from the left pump and 42.5 l / min of the right pump to the hydraulic system to the actuators (power cylinders). The power take-off for the drive of the pumps is carried out from the tractor gearbox using a step-up gear.
The gearbox is assembled in a cast iron body, which is flanged to the front of the tractor transmission body, on the left along the course of the latter.
A spur gear sits on the primary spline shaft, which meshes with the gear of the tractor drive pulley and the gear shaft of the reduction gear.
The following three gearbox settings are possible.
- If the input shaft and pinion shaft rotate, both pumps are running.
- If the roller is rotating and the pinion shaft is off, only one pump is running.
- If the main gear of the reducer is disengaged from the gear of the drive pulley of the tractor, both pumps do not work.
The gearbox is turned on and off by turning the lever associated with the control shaft.
The pumps are mounted on a cast iron gearbox housing. The pumps are driven by the tractor gearbox and supply the working fluid from the oil tank (with a capacity of 200 l) under a pressure of 75 kg / cm2 through the steam distributors to the power cylinders. From the power cylinders, the used oil flows back to the tank through the drain lilies through the filters.
Below is the device of the hydraulic pump ( rice. 45). A flange 7 is bolted to the pump casing 1, closed by a cover 11. In the casing, on bearing supports, a drive shaft 3 with seven pistons is installed.
The connecting rods 17 of the pistons with their ball heads are rolled in the flange part of the drive shaft 3.
At the second ball end of the connecting rods, the pistons 16 themselves are attached in the amount of seven pieces.
The pistons enter the cylinder block 10, which is mounted on a bearing support 9 and the action of the spring 12 is in close contact with the distributor 15. The latter, in turn, is pressed tightly against the cover 11 by the force of the same spring. To prevent the distributor from turning, it is locked with a pin.
Rotation from the drive shaft to the cylinder block is driven by a universal joint 6.
Lip seal 4, located in the front cover 2 of housing 1, serves as a barrier to leakage working fluid from the non-working cavity of the pump to the drive reducer.
The drive shaft 3 with its ground part is connected to the gearbox and receives rotation from the latter. The cylinder block 10 receives rotation from the drive shaft by means of a universal joint 6.
Due to the inclination of the axis of the cylinder block to the axis of the drive shaft, the pistons 16, when the block rotates, reciprocate. The angle of inclination affects the length of the piston stroke and, consequently, its performance.
In this pump, the tilt angle is constant and equal to 30 °.
To understand the principle of operation of the pump, consider the operation of only one piston.
Piston 16 makes one double stroke in one revolution of the cylinder block.
The extreme left and right positions correspond to the beginning of suction and discharge. When the piston moves to the left (when the block is rotated clockwise), suction occurs, when the piston moves to the right, it is pumped.
The suction and discharge positions are coordinated with the location of the hole 14 relative to the suction and discharge grooves (the grooves are oval, they are not visible in the figure) of the distributor 15.
During the suction process, the opening 14 of the block is positioned against the suction grooves of the distributor connected to the suction channel. When pumped, the hole 14 is positioned against the discharge slots connected to the discharge port.
At the same time, the remaining six pistons work in the same way.
Oil from the working cavity of the pump to the non-working one is drained into the working fluid tank through the drain hole 5.
Overpressure rise is limited by two safety valves installed on each pump.
Hydraulic cylinders are designed to carry out all movements of the excavator working bodies. On excavator E-153A installed nine cylinders ( rice. 47) piston type with rectilinear reciprocating rod movement.
During the movement of the piston rod, the cavity of the cylinder is connected to the pumping line, and the other to the drain line. The direction of movement of the rod is set by the lever of the hydraulic control box. Power cylinders are the executive bodies of the hydraulic conduit of the machine.
All cylinders have an inner diameter of 80 mm, with the exception of the boom cylinder, which is 120 mm in diameter. The rod diameter for all cylinders is 55 mm.
All cylinders (except swing cylinder) are double-acting cylinders.
Double-acting hydraulic cylinder ( rice. 46) consists of the following main parts: pipe 1, rod 29 with piston 9, front cover 27 and rear cover 5, corner fittings 7 and seals.
Pipe 1, which creates the main working volume of the cylinder, has a carefully machined inner surface. At the ends of the pipe there is an external thread for attaching caps 27 and 5 to the pei.
The bulldozer cylinder additionally has a thread in the middle of the pipe. An additional thread is required to secure the trunnion crosshead (fig. 76).
Boom, arm, bucket and slew cylinder rods 29 ( rice. 46) are hollow and consist of a pipe 28, a shank 13 and an ear 21, welded together.
The remaining cylinder rods are made of solid metal.
The cylinder rod moves in the bronze bushing 24 of the front cover.
For better wear resistance and corrosion resistance, the working surface of the stem is chrome plated.
A piston 9 with two collars 10 supported by stops 11 and a cone 12 is mounted on the free stem shank.
The cone, together with the ring, forms a damper, which serves to cushion the impact at the end of the stroke when the stem is extended to the extreme position.
The piston, stops and cone are fastened with a nut 4 and a lock washer 3.
The piston 9 has ledges on both sides to accommodate cuffs 16. Inside the piston there is an annular groove with an O-ring 2, which serves to prevent fluid from flowing from one cavity of the cylinder to another along the rod. There is a casing on the stem shank, which, in the extreme left position, enters the hole in the rear cover and forms a damper that softens the blow at the end of the stroke.
The piston serves as a support for the rod, and together with the seals it reliably divides the cylinder into two cavities, into which oil flows into one or the other.
The rear covers of all cylinders, with the exception of the bulldozer cylinder, are deaf and in their tail section has an ear with a pressed-in hardened bushing 6 for the articulation of the cylinder.
The threaded part of the cover has an annular groove with an O-ring 8, which serves to prevent fluid leaks from the cylinder.
The rear cylinder cover of the bulldozer has a central through-joint for supplying fluid through a nipple bolted to the cover.
The rear covers of the boom, stick, bucket and shoe cylinders have central and lateral bores that interconnect and form a working fluid channel.
Rear slewing cylinder covers have channels similar to those in the boom, stick and shoe cylinder covers.
Through these channels, the inoperative cavities of the cylinders are connected to each other with the help of fittings 7, a steel pipe and a breather.
The front cover 27 is screwed onto the pipes. For the passage of the stem in the cover there is a hole with a bronze bushing 24 pressed into it. Inside the cover has two ledges: the collar 16 abuts against the first, supported from axial displacement by the collar ring 25 and the retaining spring ring 26; in the second, the ring 14 abuts, forming a damper together with the cone 12 on the rod and limiting the piston stroke. On the other hand, a cover 18 is screwed onto the front cover, which secures the washer 19 and the wiper 20.
There is a hole on the side of the cover for transferring liquid through the fitting.
All covers have key slots and lock nuts.
The angle fitting is bolted to the cylinder and sealed with a rubber ring 15.
For smooth operation hydraulic cylinders, worn seals and wipers should be promptly replaced. Make sure that the cylinder rods are free of nicks and scratches. Periodically tighten the connections of the fittings, since if there is a gap between the fitting and the roof, the seals are quickly destroyed.
Hydraulic valves, or control boxes, are the main components of excavator control mechanisms. They are designed to distribute the working fluid coming from the supply hydraulic pumps to the power cylinders, of which there are nine pieces on the excavator ( rice. 47). They all have their own purpose:
- a) the boom cylinder is designed to raise and lower it;
- b) two cylinders of the handle - to communicate the movement of the handle along the radius in one direction or the other;
- c) bucket cylinder - for turning the bucket (when working with a back shovel) and for opening the bottom (when working with a straight shovel);
- d) bulldozer cylinder - for lowering or raising the blade;
- e) two turning cylinders - to communicate the rotary movement of the steering column;
- f) two cylinders of support shoes - for lifting and lowering the latter during excavation.
Left box ( rice. 47), which distributes the working fluid over the cylinders of the boom, support shoes and the steering column, consists of three pairs of rigidly interconnected throttles and spools 1. Shunt valve 2 is used to connect the working cavities of the boom power cylinder to each other and to the hydraulic drive drain line. Four spring zero-setting 4 return the hydraulic controls to the neutral (zero) position. Speed controller 3 automatically equalizes the pressure on the feed pump and the final elements.
The right box, connected to the right rear pump, distributes fluid to the arm, bucket and dozer cylinders. There is no shunt valve in this box; there is one shut-off valve 6 and two safety valves 7 and 8. Otherwise, the design of the boxes is the same.
For one of the excavator mechanisms to work, it is necessary to move the corresponding throttle-spool pair up or down, depending on which direction the mechanism should move. The left component of this pair is a throttle that changes the oil flow in magnitude, and the right component is a spool that changes the oil note in direction.
Oil tank 17 ( rice. 47) is a punch-welded structure made of 1.5 mm thick sheet steel. It consists of a rectangular-section body, inside of which four baffles are welded in, designed to calm the working fluid and separate the emulsion.
The top of the tank is closed with a stamped lid with an oil-resistant rubber gasket. In the center of the lid there is a rectangular hole where the filter tank 12 is inserted, which serves for partial oil purification.
In the lower part of the tank, two fittings are welded through which oil enters the pumps, and there is a hole closed with a plug, through which oil is drained from the tank as needed.
Three cylindrical wire filters are inserted into the tank from the sides. The tank has an inspection window 10, which allows you to monitor the level of the working fluid in the tank. Conical funnels 11 give direction to the flow of the working fluid and increase its speed. The safety valve 8 in the filter tank is adjusted to a pressure of 1.5 kg / cm2. At higher pressure, oil flows out through the drain hole of the valve.
All tank connections are hermetically sealed, and only through the air filter the inner cavity of the tank is connected to the atmosphere in order to avoid an increase in pressure in the tank.
The supply of the working fluid from the pumps to the hydraulic distribution boxes, hydraulic cylinders and discharge into the tank is carried out by means of seamless steel pipes, rubber hoses and connecting fittings.
Pipes with a diameter of 28 X 3 are installed on the discharge and power lines, a 35 X 2 pipe is installed on the power common line from the distributors to the working fluid tank. The rest of the hydraulic pipelines are made of pipes with a diameter of 22 X 2 mm. The supply of the working fluid from the tank to the pumps is carried out by two durit hoses with a diameter of 25 X 39.5.
In places where the working fluid is supplied to the moving mechanisms of the excavator, hoses are used high pressure... The 20 X 38 hoses fit on the boom and stick cylinder only, the 12 X 25 hoses fit all other cylinders.
All elements of the hydroiropod - pipes, hoses - are connected to each other using 7 ( rice. 46).
62 63 64 65 66 67 68 69 ..Piston pumps and excavator motors
Piston pumps and hydraulic motors are widely used in hydraulic drives of a number of excavators, both on mounted and on many full-revolving machines. The most widely used are rotary piston pumps of two types: axial piston and radial piston. -
Excavator Axial Piston Pumps and Motors - Part 1
Their kinematic basis is crank mechanism, in which the cylinder moves parallel to its axis, and the piston moves with the cylinder and simultaneously, due to the rotation of the crank shaft, moves relative to the cylinder. When the crank shaft is turned by an angle y (Fig. 105, a), the piston moves with the cylinder by a value and relative to the cylinder by an amount c. Rotation of the plane of rotation of the crank shaft around the y-axis (Fig. 105, b) at an angle of 13 also leads to the movement of point A, in which the crank pin is pivotally connected to the piston rod.
If instead of one we take several cylinders and arrange them around the circumference of the block or drum, and replace the crank with a disk whose axis is rotated relative to the axis of the cylinders by an angle of 7, and 0 4 y = 90 °, then the plane of rotation of the disk will coincide with the plane of rotation of the crank shaft. Then a schematic diagram of an axial pump will be obtained (Fig. 105, c), in which the pistons move in the presence of an angle y between the axis of the cylinder block and the axis of the drive shaft.
The pump consists of a stationary distributor disk 7, a rotating block 2, pistons 3, rods 4 and an inclined disk 5, pivotally connected to the rod 4. Arc windows 7 are made in the distributor disk 7 (Fig. 105, d) through which the liquid is sucked in and pumped pistons. Bridges of width bt are provided between the windows 7 to separate the suction cavity from the discharge cavity. When the block rotates, the holes of the 8 cylinders are connected either with the suction cavity or with the discharge cavity. When the direction of rotation of block 2 is changed, the functions of the cavities change. To reduce fluid leaks, the end surface of block 2 is carefully rubbed against the distributor disc 5. Disc 5 rotates from shaft b, and cylinder block 2 rotates with the disc.
The angle y is usually taken equal to 12-15 °, and sometimes it reaches 30 °. If the angle 7 is constant, then the volumetric flow rate of the pump is constant. When the value of the angle 7 of inclination of the disc 5 changes in operation, the stroke of the pistons 3 changes by one revolution of the rotor and, accordingly, the pump flow changes.
A diagram of an automatically controlled axial piston pump is shown in Fig. 106. In this pump, the feed regulator is a washer 7, connected to the shaft 3 and connected to the piston 4. On the one hand, the spring 5 acts on the piston, and on the other, the pressure in the pressure head line. When the shaft 3 rotates, the washer 7 moves the plungers 2, which suck in the working fluid and pump it into the hydraulic line. The flow rate of the pump depends on the inclination of the washer 7, i.e., on the pressure in the pressure head line, which in turn changes from external resistance. For low-power pumps, the pump flow can also be adjusted manually by changing the inclination of the washer; for more powerful pumps, a special amplifying device is used.
Axial piston motors are designed in the same way as pumps.
Many mounted excavators use a non-adjustable axial piston pump-hydraulic motor with an inclined block NPA-64 (Fig. 107). The cylinder block 3 is rotated from the shaft / through the universal joint 2. The shaft 1, driven by the engine, is supported by three ball bearings. Pistons 8 are connected to the shaft 1 by rods 10> whose ball heads are rolled in the flange part of the shaft. Cylinder block 3 "rotating on a ball bearing 9, is located in relation to the shaft 1 at an angle of 30 ° and is pressed by a spring 7 to the distributor disc b, which is pressed against the cover by the same force. The liquid is supplied and discharged through the windows 4 in the cover 5. Lip seal 11 in the pump front cover prevents oil leakage from the pump's non-working cavity.
The pump flow per one shaft revolution is 64 cm3. At 1500 rpm of the shaft and an operating pressure of 70 kgf / cm2, the pump flow is 96 l / min, and the volumetric efficiency is 0.98.
In the NPA-64 pump, the cylinder block axis is located at an angle to the axis of the drive shaft, which determines its name - with an inclined block. In contrast to it, in axial pumps with an inclined disk, the axis of the cylinder block coincides with the axis of the drive shaft, and the axis of the disk is located at an angle to it, with which the piston rods are pivotally connected. Consider the design of an adjustable axial piston pump with a swash plate (Fig. 108). The peculiarity of the pump is that the shaft 2 and the swash plate b are connected to each other using a single or double cardan mechanism 7. The working volume and flow of the pump are regulated by changing the slope disk b relative to block 8 of cylinders 3.
105 Diagrams of an axial piston pump:
A is the action of the piston,
B - pump operation, c - constructive, d - action of a stationary distribution disk;
1 - stationary distribution disc,
2 - rotating block.
3 - piston,
5 - swash plate,
7 - arc window,
8 - cylindrical hole;
A - the length of the full section of the arc window
106 Schematic of a variable displacement axial piston pump:
1 - washer,
2 - plunger,
3 - shaft,
4 - piston,
5 - spring
In the spherical bearings of the inclined disk 6 and the pistons 4 are fixed by the ends of the connecting rods 5. During operation, the connecting rod 5 is deflected by a small angle relative to the axis of the cylinder J, therefore the lateral component of the force acting on the bottom of the piston 4 is negligible. The torque on the cylinder block is determined only by the friction of the end of the block 8 about the distribution disc 9. The magnitude of the moment depends on the pressure in the cylinders 3. Almost all the torque from the shaft 2 is transmitted to the swash plate 6, since when it rotates, the pistons 4 move, displacing the working fluid from the cylinders 3. Therefore, a highly loaded element in such pumps is the cardan mechanism 7, which transfers all the torque from the shaft 2 to the disk 6. The cardan mechanism limits the angle of inclination of the disk 6 and increases the dimensions of the pump.
The cylinder block 8 is connected to the shaft 2 through a mechanism 7, which allows the block to self-align over the surface of the distribution disc 9 and transfer the friction moment between the ends of the disc and the block to the shaft 2.
One of the positive features of this type of variable speed pump is the convenient and simple supply and discharge of the working fluid.
Hydraulic transmissions of road machines
Hydraulic transmissions are widely used in road machines, replacing mechanical transmissions due to significant advantages: the ability to transmit high power; stepless transmission of forces; the possibility of branching the power flow from one engine to different working bodies; rigid connection with the mechanisms of the working bodies, providing the possibility of their forced burial and fixation, which is especially important for the cutting bodies of earth-moving machines; ensuring accurate speed control and reversal of the movement of the working bodies by a fairly simple and convenient control of the handles of the distribution devices; the ability to design any transmission of machines without bulky cardan transmission and compose them using standardized elements and extensive use of automated devices.
In hydraulic transmissions, the working element that transfers energy is the working fluid. Used as a working fluid mineral oils a certain viscosity with anti-wear, antioxidant, antifoam and thickening additives that improve the physical and performance properties of oils. Industrial oil IS-30 and MS-20 with a viscosity at a temperature of 100 ° C 8-20 cSt (pour point -20 -40 ° C) is used. To increase the efficiency and durability of machines, the industry produces special hydraulic oils MG-20 and MG-30, as well as VMGZ (pour point -60 ° C), intended for all-season operation of hydraulic systems of road, construction, logging and other machines and ensuring their operation also in northern regions, regions of Siberia and the Far East.
According to the principle of operation, hydraulic transmissions are divided into hydrostatic (hydrostatic) and hydrodynamic. In hydrostatic transmissions, the pressure of the working fluid (from the pump) is used, which is converted into a forward-reverse mechanical movement using hydraulic cylinders or into a rotary movement using hydraulic motors (Fig. 1.14). In hydrodynamic transmissions, torque is transmitted by changing the amount of working fluid flowing in the impellers, enclosed in a common cavity and performing the functions of a centrifugal pump and turbine (fluid couplings and torque converters).
Rice. 1.14. Hydrostatic transmission schemes:
a - with a hydraulic cylinder; b - with a hydraulic motor; 1 - hydraulic cylinder; 2 - pipeline; 3 - hydraulic valve; 4 - pump; 5 - drive shaft; 6 - liquid tank; 7 - hydraulic motor
Hydrostatic transmissions are performed both in open and in closed (closed) circuits with pumps of constant and variable delivery (unregulated and adjustable). In open circuits, the liquid circulating in the system, after being triggered in the power element of the drive, returns to the tank under atmospheric pressure (Fig. 1.14). In closed circuits, the circulating fluid is directed to the pump after operation. To eliminate jet breaks, cavitation and leaks in a closed system, make-up is performed due to a small pressure head from a make-up tank included in the hydraulic system.
In circuits with pumps of constant supply, the speed control of the working bodies is carried out by changing the flow areas of the throttles or incomplete switching on of the valve spools. In circuits with variable feed pumps, the speed control is carried out by changing the working volume of the pump. Circuits with throttle control are simpler, however, for the most loaded machines and when transmitting high powers, it is recommended to use circuits with volumetric control of the system.
Recently, hydrostatic traction transmission has been widely used in road vehicles. For the first time, such a hydraulic transmission was used on a small-sized tractor (see Fig. 1.4). Such a tractor with a set attachments intended for auxiliary work in various sectors of the national economy. It is a short-base car with a diesel power of 16 liters. s, the greatest tractive effort is 1200 kgf, the forward and backward movement speed is from zero to 14.5 km / h, the base is 880 mm> the track is 1100 mm, the weight is 1640 kg.
The diagram of the hydrostatic transmission of the tractor is shown in Fig. 1.15. The engine, through a centrifugal clutch and a transfer gearbox, imparts movement to two pumps that feed the hydraulic motors, respectively, of the right and left sides of the machine.
Rice. 1.15. The layout diagram of the hydrostatic transmission of a small-sized skid steer tractor:
1 - dvcgatel; 2 - centrifugal clutch; 3 - transfer gearbox; 4 - make-up pump; 5 - hydraulic booster; 6, 16 - high pressure pipelines; 7 - main filter; 8 - travel hydraulic motor; 9 - valve box; 10, 11 - automatic valves; 12 - check valve; 13, 14 - safety valves; 16 - into a variable flow hydraulic pump) 17 - gear final drive
The torque of the hydraulic motor is increased by the gear final drive and is transmitted to the front and rear wheels of each side. All wheels of the tractor are driven. The hydraulic circuit of the transmission of each side includes a pump, a hydraulic motor, a hydraulic booster, a feed pump, a main filter, a valve box, and high pressure pipelines.
When the pump is operating, the working fluid under pressure, depending on the overcome resistance, enters the hydraulic motor, drives its shaft into rotation and then returns to the pump.
Its leakage through the gaps in the associated parts is compensated for by a boost pump built into the traction pump housing. The make-up is controlled automatically by valves. The working fluid for it is supplied to the line, which is the drain. If there is no need for make-up, then the entire flow rate of the make-up pump is directed to drain into the tank through the valve. Safety valves limit the maximum allowable pressure in the system, equal to 160. kgf / cm2. The make-up pressure is maintained at the level of 3-6 kgf / cm2.
Rice. 1.16. Fluid coupling diagram:
1 - drive shaft; 2 - pump wheel; 3 - case; 4 - turbine wheel; 5 - driven shaft
A variable feed pump can change the minute flow of the working fluid, that is, swap the suction and discharge lines. The rotational speed of the hydraulic motor shaft is directly proportional to the pump flow: the more fluid is supplied, the higher the rotational speed, and vice versa. Setting the pump to zero flow results in complete deceleration.
Thus, the hydrostatic transmission completely eliminates the clutch, gearbox, final drive, cardan shaft, differential and brakes. The functions of all these mechanisms are performed by a combination of variable displacement pump and hydraulic motor operation.
Hydrostatic transmissions have the following advantages: full use of engine power in all operating modes and protection from overloads; good starting performance and the presence of the so-called creeping speed with high traction; stepless, stepless speed control over the entire range from zero to maximum and vice versa; high maneuverability, ease of control and maintenance, self-lubrication; lack of rigid kinematic connections between transmission elements; independence of the location of the engine with a pump and hydraulic motors on the chassis, i.e., favorable conditions for choosing the most rational layout of the machine.
Hydrodynamic transmissions as the simplest mechanism have a fluid coupling (Fig. 1.16), consisting of two impellers, pump and turbine, each of which has flat radial blades. The pump wheel is connected to a drive shaft driven by a motor; a turbine wheel with a driven shaft is connected to a gearbox. Thus, there is no rigid mechanical connection between the Engine and the gearbox.
Rice. 1.17. Torque converter U358011AK:
1 - rotor; 2 - disk; 3 - glass; 4 - reactor; 5 - case; 6 - turbine wheel; 7 - pump wheel; 8 - cover; 9, 10 - sealing rings; 11 - driven shaft; 12 - jet; 13 - freewheel mechanism; 14 - drive shaft
If the motor shaft rotates, then the impeller throws the working fluid in the coupling to the periphery, where it enters the turbine wheel. Here it gives up its kinetic energy and, having passed between the turbine blades, enters the pump wheel again. As soon as the torque transmitted to the turbine is greater than the drag torque, the driven shaft will begin to rotate.
Since there are only two impellers in the fluid coupling, then under all operating conditions the torques on them are equal, only the ratio of their rotational speeds changes. The difference between these frequencies, referred to the rotational speed of the impeller, is called slip, and the ratio of the rotational speeds of the turbine and impeller is the efficiency of the fluid coupling. The maximum efficiency reaches 98%. The fluid coupling ensures smooth starting of the machine and reduces dynamic loads in the transmission.
Hydrodynamic transmissions in the form of torque converters are widely used on tractors, bulldozers, loaders, motor graders, rollers and other construction and road machines. The torque converter (Fig. 1.17) acts similarly to a fluid coupling.
The impeller, sitting by means of a rotor on a drive shaft connected to the engine, creates a circulating fluid flow that transfers energy from the impeller to the turbine. The latter is connected to the driven shaft and to the transmission. An additional stationary impeller - the reactor allows for a higher torque on the turbine impeller than on the pumping one. The degree of torque increase on the turbine wheel depends on gear ratio(the ratio of the speeds of rotation of the turbine and pump wheels). When the driven shaft speed rises to the engine speed, the freewheel roller locks the driven and driven parts of the converter, allowing power to be transferred directly from the engine to the driven shaft. Sealing inside the rotor is carried out by two pairs of cast iron rings.
The torque will be maximum when the turbine wheel is not rotating (locking mode), minimum - in the mode idle move... With an increase in external resistance, the torque on the driven shaft of the torque converter automatically increases several times compared to the engine torque (up to 4-5 times in simple and up to 11 times in more complex designs). As a result, the use of the power of the internal combustion engine under variable loads on the actuators is increased. Automation of transmissions with torque converters is greatly simplified.
When external loads change, the torque converter completely protects the engine from overloads, which cannot stop even when the transmission is locked.
In addition to automatic control, the torque converter also provides controlled speed and torque control. In particular, by adjusting the speeds, assembly speeds for crane equipment are easily achieved.
The described torque converter (U358011AK) is installed on self-propelled road vehicles with a 130-15O hp engine. with.
Pumps and motors. In hydraulic transmissions, gear, vane and axial piston pumps are used - To convert mechanical energy into energy of the fluid flow and hydraulic motors (reversible pumps) - to convert the energy of the fluid flow into mechanical energy. The main parameters of pumps and hydraulic motors are the volume of the working fluid displaced per revolution (or double piston stroke), the nominal pressure and the nominal speed, and the auxiliary parameters are the nominal supply or flow rate of the working fluid ’nominal torque, as well as the overall efficiency.
The gear pump (Fig. 1.18) has two cylindrical gears, made integral with the shafts, which are enclosed in an aluminum casing.
Rice. 1.18. Gear pump NSh-U series:
1, 2 - retaining rings of the seal; 3 - seal; 4 - O-shaped seals; 5 - leading gear wheel; 6 - case; 7 - bronze bearing bushings; 8 driven gear; 9 - cover fixing bolt; 10 - cover
The protruding end of the drive gear shaft is spline-connected to the drive device. The shafts of the gears rotate in bronze bushings, which simultaneously serve as seals for the end surfaces of the gears. The pump provides hydraulic compensation end clearances, due to which, during operation, a high volumetric efficiency of the pump is maintained for a long time. The protruding shaft is sealed. The pumps are bolted to the cover.
Table 1.7
Technical characteristics of gear pumps 
Rice. 1.19. Vane (vane) pump MG-16:
1 - blade; 2 - holes; 3 - stator; 4 - shaft; 5 - cuff; 6 - ball bearings; 7 - drainage hole; 8 - cavities under the blades; 9 - rubber ring) 10 - drain hole; 11 - drain cavity; 12 - annular ledge; 13 - cover); 14 - spring; 15 - spool; 16 - rear disc; 17 - box; 18 - cavity; 19 - hole for supplying liquid with high pressure; 20 - hole in the rear disc 21 - rotor; 22 - front disc; 23 - annular channel; 24 - supply hole; 25 - case
Gear pumps are produced in the NSh series (Table 1.7), and the pumps of the first three brands are completely unified in design and differ only in the width of the gear wheels; the rest of their parts, with the exception of the body, are interchangeable. NSh pumps can be made reversible and can operate as hydraulic motors.
In a vane (vane) pump (Fig. 1.19), the rotating parts have a small moment of inertia, which makes it possible to change the speed with high accelerations, with slight increases in pressure. The principle of its operation is that the rotating rotor, with the help of sliding vane blades, freely sliding in the slots, sucks liquid into the space between the blades through the inlet hole and feeds it into the drain cavity further through the drain hole to the working mechanisms.
Vane pumps can also be made reversible and used to convert the energy of the fluid flow into mechanical energy of the rotary motion of the shaft. The characteristics of the pumps are given in table. 1.8.
Axial piston pumps are mainly used in hydraulic drives with increased pressure in the system and relatively high powers (20 hp and more). They allow short-term overloads and operate with high efficiency. Pumps of this type are sensitive to oil contamination and therefore, when designing hydraulic drives with such pumps, they provide for a thorough filtration of the liquid.
Table 1.8
Technical characteristics of vane (vane) pumps 
The pump type 207 (Fig. 1.20) consists of a drive shaft, seven pistons with connecting rods, radial and double radial-thrust ball bearings, a rotor, which is centered by a spherical distributor and a central pin. During one revolution of the drive shaft, each piston makes one double stroke, while the piston coming out of the rotor sucks the working fluid into the released volume, and when moving in the opposite direction displaces the fluid into the pressure line. The change in the magnitude and direction of the flow of the working fluid (reversal of the pump) is carried out by changing the angle of inclination of the rotary housing. With an increase in the deviation of the rotary housing from the position at which the axis of the drive shaft coincides with the axis of the rotor, the stroke of the pistons increases and the pump flow changes.
Rice. 1.20. Axial piston variable pump type 207:
1 - drive shaft; 2, 3 - ball bearings; 4 - connecting rod; 5 - piston; 6 - rotor; 7 - spherical distributor; 8 - rotary body; 9 - central spike
Table 1.9
Technical characteristics of variable axial piston pumps 
The pumps are available in various flow rates and capacities (Table 1.9) and in various designs: with different connection methods, with make-up, with check valves and with power regulators of type 400 and 412. Power regulators automatically change the angle of inclination of the rotary casing depending on the pressure maintaining a constant drive power at a certain drive shaft speed.
To provide a greater flow, double pumps of type 223 are produced (table 1.9), consisting of two unified pumping units of the pump of type 207, installed in parallel in a common casing.
Axial piston fixed displacement pumps type 210 (Fig. 1.21) are reversible and can be used as hydraulic motors. The design of the pumping unit for these pumps is similar to the pump of type 207. Pumps-hydraulic motors of type 210 produce different flow rates and powers (Table 1.10) and, like pumps of type 207, in various designs. The direction of rotation of the pump drive shaft is right (from the shaft side), and for the hydraulic motor - right and left.
Rice. 1.21. Axial piston pump type 210:
1 -in the drive shaft; 2, 3 - ball bearings; 4 - swivel washer; 5 - connecting rod 6 -e piston; 7 - rotor; 8 - spherical distributor; 9 - cover; 10 - central thorn; 11 - case
The NPA-64 pump is produced in one version; it is the prototype of the 210 family of pumps.
Hydraulic cylinders. In mechanical engineering, hydraulic power cylinders are used to convert the pressure energy of the working fluid into mechanical work mechanisms with reciprocating motion.
Table 1.10
Technical characteristics of axial piston fixed pumps-hydraulic motors 
According to the principle of action, hydraulic cylinders are single-acting and double-acting. The former develop force only in one direction - on pushing out the piston rod or plunger. Reverse move is performed under the action of the load of that part of the machine with which the stem or plunger is mated. These cylinders include telescopic cylinders, which provide a large stroke due to the extension of the telescopic rods.
Double-acting cylinders operate under the action of fluid pressure in both directions and are available with a double-acting (through) rod. In fig. 1.22 shows the most widely used double-acting normalized hydraulic cylinder. It has a body in which a movable piston is placed, secured to the rod by means of a castellated nut and a cotter pin. The piston is sealed in the body with cuffs and a rubber O-ring inserted into the stem bore. The cuffs are pressed against the cylinder walls by discs. On the one hand, the body is closed by a welded head, on the other - by a screwed cover with a journal box through which a stem with an eyelet at the end passes. The stem is also sealed by a disc-collar in combination with a rubber O-ring. The main load is taken up by the cuff, and the preloaded O-ring ensures the tightness of the movable joint. To increase the durability of the lip seal, a protective fluoroplastic washer is installed in front of it.
The stem outlet is sealed with a wiper gland that cleans the stem from adhering dust and dirt. The cylinder head and cover have channels and threaded holes for connecting the oil supply lines. The lugs in the cylinder and the rod are used to connect the cylinder by means of hinges to the supporting structures and working bodies. When oil is supplied to the piston cavity of the cylinder, the rod extends, and when supplied to the rod cavity, it is drawn into the cylinder. At the end of the piston stroke, the stem shank, and at the end of the opposite stroke, the stem sleeve are recessed into the bores of the head and cover, while leaving narrow annular gaps for fluid displacement. Resistance to the passage of fluid in these gaps slows down the stroke of the piston and softens (dampens) the shock when it rests against the head and housing cover.
In accordance with GOST, the main standard sizes of unified hydraulic cylinders G with an inner diameter of a cylinder from 40 to 220 mm with various lengths and strokes for a pressure of 160-200 kgf / cm2 are produced. Each standard size of the hydraulic cylinder has three basic versions: with lugs on the rod and the cylinder head with bearings; in an eye on the rod and a trunnion on the cylinder for its rocking in one plane; with a rod having a threaded hole or end, and at the end of the cylinder head - threaded holes for bolts for fastening working elements.
Hydraulic valves control the operation of hydraulic motors of volumetric hydraulic systems, direct and shut off oil flows in pipelines connecting hydraulic units. Most often, spool valves are used, which are produced in two versions; monoblock and sectional. In a monoblock valve, all spool sections are made in one cast body, the number of sections is constant. In a sectional distributor, each spool is installed in a separate housing (section), which is connected to the same adjacent sections. The number of sections of the separable distributor can be reduced or increased by rewiring. In operation, in the event of a malfunction of one spool, one section can be replaced without rejecting the entire distributor as a whole.
Monoblock three-piece valve (fig. 1.23) has a body in which there are three spools and a bypass valve resting on the seat. By means of the handles installed in the cover, the driver moves the spools to one of four operating positions: neutral, floating, lifting and lowering the working body. In each position, except for the neutral one, the spool is fixed by a special device, and in the neutral position - by a return (zero-setting) spring.
From the fixed lifting and lowering positions, the spool returns to neutral automatically or manually. The fixing and return devices are closed by a cover bolted to the bottom of the body. The spool has five grooves, an axial hole at the lower end and a transverse hole at the upper end for the ball drive of the handle. A transverse channel connects the spool axial bore to the high pressure cavity of the body in the up and down positions.
Rice. 1.23. Monoblock three-piece hydraulic valve with manual control!
1 - top cover; 2 - spool; 3 -. frame; 4 - booster; 5 - croutons; 6 - bushing; 7 - retainer body; 8 - retainer; 9 - shaped sleeve; 10 - returnable spring; 11 - spring glass; 12 - spool screw; 13 - bottom cover; 14 sh. bypass valve seat; 15 - bypass valve; 16 - handle
The valve ball is pressed by a spring to the end face of the spool hole connected to its surface by a transverse channel by means of a booster and a crouton. The spool is surrounded by a bushing connected to the crouton by means of a pin, which is passed through the oblong spool windows.
When the pressure in the system rises to the maximum, the valve ball is pushed down under the action of the liquid flowing through the transverse channel from the rise or fall cavity into the axial hole of the spool. In this case, the booster pushes down the cracker 5 together with the sleeve until it stops in the sleeve. For the liquid, an outlet into the drain cavity opens, and the pressure in the discharge cavity of the distributor decreases, Valve 15 cuts off the drain cavity from the discharge cavity, since it is constantly pressed against the seat by a spring. The valve belt has an opening and an annular gap in the housing bore, through which the pressure and control cavities communicate.
When working with normal pressure, the same pressure is set in the cavities above and below the shoulder of the bypass valve, since these cavities are communicated by means of an annular gap and a hole in the shoulder. Parts 7-12 constitute a device for fixing the positions of the spool.
pa fig. 1.24 shows the positions of the parts of the fixing Device in relation to the working positions of the spool.
Rice. 1.24. Scheme of operation of the locking device of the spool of the monoblock hydraulic valve:
a - neutral position; b - rise; c - lowering; d - floating position; 1 - release sleeve; 2 - upper retaining spring; 3 - retainer body; 4 - lower retaining spring; 5 - support sleeve; 6 - spring sleeve; 7 - spring; 8 - lower spring cup; 9 - screw; 10 - bottom cover of the distributor; 11 ~ distributor body; 12 - spool; 13 - lowering cavity
The neutral position of the spool is fixed by a spring, which expands the glass and sleeve to the stop. In the other three positions, the spring is compressed more and tends to expand to return the spool to the neutral position. In these positions, the annular retaining springs sink into the grooves of the spool and lock it against the body.
The driver can return the spool to neutral. When the handle moves, the spool moves from its place, the annular springs are squeezed out of the spool grooves, and. it is returned to the neutral position by an expanding spring.
The spool automatically returns to the neutral position when the pressure in the lifting or lowering cavities rises to the maximum. In this case, the inner ball of the spool pushes the bushing down, and the end of this bushing pushes the annular spring into the housing groove. The spool is released from locking. Further movement of the spool to the neutral position is carried out by a spring acting on the spool through the sleeve and the glass, held on the spool by a screw. Known distributors with ball clamps instead of annular springs and with a modified design of the booster and the ball valve.
When the spool is in the neutral position, the cavity above the shoulder of the bypass valve is connected to the drain cavity of the valve distributor. In this case, the pressure in the control cavity decreases in comparison with the pressure in the discharge cavity, due to which the valve rises, opening the way to the drain, and the spool cuts off the cavity of the slave cylinder (or the pressure and drain oil lines of the hydraulic motor) from the pressure and drain pipelines of the system.
In the lifting position of the working element, the spool connects the pressure valve with the corresponding cylinder cavity and, at the same time, the other cylinder cavity with the distributor drain channel. At the same time, it closes the channel of the control cavity above the bypass valve shoulder, due to which the pressure in it and in the discharge cavity (under the valve shoulder) is equalized, the spring presses the valve against the seat, cutting off the drain cavity from the discharge cavity.
In the position of the lowering of the working element, the spool changes to the opposite connection of the pressure and drain cavities with the cavities of the slave cylinder. At the same time, it simultaneously closes the channel of the control cavity of the bypass valve, due to which the valve is set to the position of stopping the bypass.
In the floating position of the working body, the spool cuts off both cavities of the slave cylinder from the pressure channel of the distributor and connects them to the drain cavity. At the same time, it connects the channel of the control cavity of the bypass valve with the drain channel of the distributor. At the same time, the pressure above the valve shoulder decreases, the valve rises from the seat, compressing the spring and opening the way for the oil from the pressure cavity to the drain cavity.
Distributors of other types and sizes are structurally different from the one described by the location and shape of the channels and cavities of the body, the belts and bores of the spools, as well as the arrangement of the bypass and safety valves. There are three-position valves that do not have a floating spool position. A float position of the spool is not required to control the hydraulic motors. The rotation of the motor in the forward and reverse directions is controlled by the installation of the spool in one of two extreme positions.
Monoblock distributors with a capacity of 75 l / min are widely used for tractor equipment and road machines: two-spool distributors of the R-75-B2A type and three-spool R-75-VZA, as well as three-spool distributors R-150-VZ with a productivity of 160 l / min.
In fig. 1.25 shows a typical (normalized) sectional valve with manual control, consisting of a pressure head, a working three-position, a working four-position and a drain section. With the neutral position of the spools of the working sections, the liquid coming from the pump through the overflow channel is freely drained into the tank. When the spool is moved to one of the operating positions, the overflow channel is closed with the simultaneous opening of the pressure and drain channels, which are alternately connected to the outlets to the hydraulic cylinders or hydraulic motors.
Rice. 1.25. Manual sectional distributor:
1 - pressure head section; 2 - working three-position section; 3, 5 - spools; 4 - working four-position section; 6 - drain section; 7 - bends; 8 - safety valve; 9 - overflow channel; 10 - drain channel; 11 - valor channel; 12 - check valve
When the spool of the four-position section is moved in the floating position, the pressure channel is closed, the overflow channel is open, and the drain channels are connected to the taps.
The pressure section has a built-in differential-action cone safety valve, which limits the pressure in the system, and a check valve, which excludes the backflow of the working fluid from the hydraulic control valve when the spool is turned on.
Three-position and four-position working sections differ only in the spool locking system. By-pass valve block and spool can be connected to the working three-position sections, if necessary. remote control... Distributors are assembled from separate unified sections - pressure workers (different in purpose), intermediate and drain. The distributor sections are bolted together. Between the sections there are sealing plates with holes, into which O-rings are installed to seal the joints. A certain thickness of the plates allows, when tightening the bolts, to have a single deformation of the rubber rings along the entire plane of the section joint. The different valve arrangements are shown in the hydraulic diagrams in the machine description.
Working fluid flow control devices. These include reversing spools, valves, throttles, filters, piping and fittings.
The reversible spool is a one-section three-position valve (one neutral and two working positions) and is used to reverse the flow of the working fluid and change the direction of movement of the actuators. Reversible spools can be manual (type G-74) and electrohydraulic control (type G73).
The electro-hydraulic spools have two electromagnets connected to the control spools that bypass fluid to the main spool. Such spools (such as ZSU) are often used in automation systems.
Valves and throttles are designed to protect hydraulic systems from excessive pressure of the working fluid. Safety valves (type G-52), safety valves with an overflow spool and check valves (type G-51) are used, designed for hydraulic systems in which the flow of working fluid is passed only in one direction.
Chokes (type G-55 and DR) are designed to regulate the speed of movement of the working bodies by changing the value of the flow of the working fluid. Chokes are used together with a regulator, which ensures a uniform speed of movement of the working bodies, regardless of the load.
Filters are designed to clean the working fluid from mechanical impurities (with a filtration fineness of 25, 40 and 63 microns) in the hydraulic systems of machines and are installed in the mains (separately mounted) or in the working fluid tanks. The filter is a glass with a lid and a sump plug. Inside the glass there is a hollow rod, on which a normalized set of mesh filter discs or a paper filter element is installed. The filter discs are pushed onto a rod and tightened with a bolt. The assembled filter bag is screwed into the lid. The paper filter element is a corrugated cylinder made of filter paper with an underlayer mesh, connected at the ends with metal caps using epoxy resin. The covers have openings for the supply and drainage of liquid, as well as a by-pass valve. The liquid passes through the filter element, enters the hollow rod, and the purified liquid enters the tank or the main line.
Pipelines and fittings. The nominal passage of pipelines and their connections should, as a rule, be equal to the inner diameter of pipes and channels of connecting fittings. The most common nominal internal diameters of pipelines are 25, 32, 40 mm, and less often 50 and 63 mm. Nominal pressure 160-200 kgf / cm2. Hydraulic drives are designed for nominal pressures of 320 and 400 kgf / cm2, which significantly reduces the size of pipelines and hydraulic cylinders.
Up to a size of 40 mm, threaded unions of steel pipes are most commonly used; for sizes above the specified, flange connections are used. Rigid pipelines are made of steel seamless pipes. Connect the pipelines by means of cutting rings, which, when tightened, are tightly squeezed around the pipe. Thus, the joint, including the pipe, the union nut, the cutting ring and the nipple, can be repeatedly disassembled and assembled without loss of tightness. For the mobility of the connection of rigid pipelines, rotary joints are used.
The car frame is reinforced with two additional frames. In addition, to improve the maneuverability of the ladder and reduce its length, the rear chassis springs have been replaced with shorter ones, the transfer case for connecting a gear pump has been modified, and the transmission to the front axle has been removed.
The ladder of the gangway consists of two parts: stationary and retractable.
The load-bearing frame of the ladder is a truss welded from rolled steel profiles. The stationary part of the staircase has eleven fixed steps and one folding one. The treads are made of steel sheets and covered with corrugated rubber. The lower part of the staircase is covered with removable panels. The stationary part is attached to the chassis frame.
The retractable part of the ladder has an exit platform to the aircraft, which is edged with elastic buffers at the points of contact with the aircraft. It is driven by a special mechanism consisting of a hydraulic pump, a bevel gearbox and a lead screw with a nut. The retractable part of the ladder is stopped automatically.
A certain position of the ladder in height corresponds to its emphasis on the retractable ladder. For unloading the wheels and springs, as well as for the stability of the ladder during embarkation and disembarkation of passengers, four hydraulic supports are installed on the car chassis. The hydraulic system of the ladder serves the hydraulic supports and the mechanism for raising and lowering the ladder. The pressure in the hydraulic system is created by the NSh-46U gear pump, driven by the engine of the UAZ-452D car through transfer case... In addition, there is an emergency hand pump.
The ladder is controlled from the driver's cab. The control lamps on the control panel signal the raising of the hydraulic supports and the fixation of the ladder at a given height. The steps of the staircase are illuminated by shades at night. To improve illumination when approaching the ladder to the aircraft, the roof of the front part of the cockpit is glazed. A headlamp is installed on the roof to illuminate the point of contact of the retractable ladder with the aircraft.
The hydraulic system of the SPT-21 ladder (Fig. 96) serves the hydraulic supports and the ladder lifting mechanism. Left-hand gear pump NSh-46U is designed to supply hydraulic units with liquid. The pump is driven car engine through the transfer case and the front propeller shaft.
Hydraulic tank is a welded construction tank, in the upper part of which there is a shut-off neck with a filter and a measuring ruler. The tank has fittings: intake, return line and drain. In the event of a failure of the main pump or its drive, the system provides an emergency hand pump installed on the rear chassis frame near the right fairing. On the chassis frame there are four hydraulic supports, two at the rear and at the front. They serve as a rigid support for the gangway at the entrance and exit of passengers, as well as for unloading the wheels and springs. A hydraulic lock is used to fill the fluid in the outlet line of the supports.
Pump NPA-64 operates in the mode of a hydraulic motor to rotate the lead screw of the lifting mechanism.
To limit overloads that may occur in the event of a malfunction of the mechanisms, the hydraulic system is equipped with a safety valve adjusted to a pressure of 7 MPa. The hydraulic system control is located on the hydraulic panel installed in the cockpit of the gangway on the right side of the driver. The panel contains a pressure gauge, control valves for hydraulic supports and a ladder.
In addition to electrical system of the car electrical equipment of the ladder SPT-21 includes systems: automatic stopping of stairs; lighting the ladder; light and sound signaling and the readiness of the gangway for boarding passengers.
The ladder automatic stop system consists of: a limit switch 6 of an electromagnetic valve 10, a signal light 8, a button for forced switching on of an electromagnetic valve 7 (Fig. 97) circuit and includes an electromagnetic valve, the spool of which connects the working line with the drain, and the ladder stops. At this time, the control lamp on the control panel lights up. When moving the stairs to another height, it is necessary to press the button for forced switching on of the electromagnetic crane.
V ladder lighting system Includes step lamps and a flight indicator lamp.
The light alarm system consists of two light boards and a relay-breaker. The car horn is used to give a sound signal, and a breaker relay is used to give an intermittent sound signal. A light board with inscriptions is attached to the railing of the retractable staircase. Lighting control, alarm control and the button for forced switching on of the electromagnetic crane are installed on the control panel in the cockpit of the ladder.
Passenger ladder TPS-22 (SPT-20)
Developed on the chassis of the UAZ-452D truck. Produced at the airport mechanization plant.
TPS-22 is intended for boarding passengers and disembarking them from the aircraft, the level of the threshold of the entrance doors of which is within 2.3-4.1 m.
The control is carried out by one driver-operator. The earlier model SPT-20 was intended for servicing aircraft at airports located in the northern regions, where the operation of ladders with battery power supplies is difficult.
A carburetor four-cylinder internal combustion engine of the UAZ-451D type is used as power equipment. The ladder of the ladder SPT-20 has a constant angle of inclination and consists of a stationary part, fixed on the ladder chassis, a retractable section with a landing pad and an additional retractable landing pad intended for servicing aircraft with a passenger door sill height of about 2 m. The upper telescopic section is extended from using a cable-block system driven by an NPA-64 hydraulic motor.
The extension of the additional platform to the forward position is carried out by a hydraulic cylinder.
Features of operation... The procedure for the operation of the ladder at the aircraft is as follows: stop the ladder at a distance of 10 ... 12 m from the aircraft and set the ladder in height for the required type of aircraft. To do this, turn off the rear axle, turn on the hydraulic pump, put the ladder control valve in the "Lift" position, press the forced switch button and hold it until the light goes out, and then, smoothly lowering the clutch pedal, start lifting;
when the jumper connecting the sides of the retractable ladder approaches, at a distance of 100 ... 150 mm to the required height indicator, painted on the lower casing of the stationary ladder, release the button;
after the automatic stop system has been triggered, the staircase will stop, and the warning lamp will light up;
the stairs are raised at the second speed, the descent at the third; after stopping the ladder, disengage the clutch, put the ladder control valve in the neutral position, turn off the hydraulic pump and prepare the ladder for movement;
all safety precautions must be observed when approaching the aircraft; after approaching the aircraft, turn off the rear axle, turn on the second speed, turn the pump, the handle of the support control valve to the “Release” position, put the ladder on the supports. Turn off the speed, put the handle of the crane in neutral position.
Give a lingering signal (3 ... 5 s) by pressing the car signal button and put the switch located on the control panel in the direction of "Disembarkation is coming";
when the ladder leaves the plane, do all the operations in reverse order, and set the alarm switch to the “No landing” position.
The ladder allows you to adjust the height of the stairs in the range of 2400 ... 3900 mm with an angle of inclination of no more than 43 °. Step steps 220 mm, width 280 mm Operating speed of the ladder movement 3 ... 30 km / h.
Maintenance.
During maintenance it is necessary:
carefully check the serviceability of units, mechanisms and systems, timely carry out preventive work;
check the condition of the helical frame of the ladder lifting mechanism on a monthly basis and lubricate it with graphite grease;
if a leak is detected in the hydraulic system, immediately find out the cause of the malfunction and eliminate it;
fill in the hydraulic system with AMG-10 oil. During operation, you need to periodically top up the hydraulic tank with fresh oil;
in the hydraulic system, once a year, it is necessary to do the following preventive work: completely drain the oil from the hydraulic system; flush the hydraulic tank; take out and wash the filter element of the filter; fill in fresh oil and bleed the system to remove air;
pump the lines by repeatedly raising and lowering the ladder, as well as releasing and removing the supports. A sign of the end of the pumping of the system is the smoothness and absence of jerks when the ladder and supports move;
the oil in the hoist gearbox should be changed at least 2 times a year. Automotive transmission oil TAP-15V should be used, and at temperatures below -20 ° C - TS 10;
lubricate the sliding ladder carriage guides with USSA graphite grease at least once a month;
lubricate the bearings of the upper assembly of the lead screw and the pump mounting bracket NSh 46 U with universal grease at least once every 3 months;
carry out preventive maintenance on the automobile chassis of the ladder in accordance with the instructions for operation of the UAZ-452D vehicle.
The ladder on the basis of the UAZ, which was attached to the "Buran" in the Central Park of Culture and Leisure in Moscow (2009): 
TPS-22 at the airfield in Yaroslavl 
TPS-22 in Yakutia 
Airport in Kuibyshev 
TPS-22 as a holiday car 
TPS-22 of the KVM company 
Description of TPS-22 
The process of joining the TPS-22 ladder with the aircraft 
E-153 excavator hydraulic equipment
Schematic diagram hydraulic system excavator E-153 is shown in Fig. 1. Each unit of the hydraulic system is made separately and installed in a specific location. All units of the system are interconnected by high pressure oil lines. The working fluid tank is mounted on special brackets on the left side in the direction of the tractor and is secured with strap ladders. Be sure to place felt gaskets between the tank and the bracket, which protect the tank walls from breakdown at the points of contact with the brackets.
Below the tank, on the gearbox housing, the drive for axial plunger pumps is installed. Each pump is connected to the working fluid tank with a separate oil line low pressure... The front pump is connected with a high pressure oil line to the large junction box, and the rear pump is connected to the small junction box.
Junction boxes are mounted and fastened on a special welded frame, which is attached to the rear wall of the enclosure rear axle tractor. The frame also provides reliable fastening of the hydraulic control levers and the fender brackets of the rear tractor wheels.
Rice. 1. Schematic diagram hydraulic equipment excavator E-153
All power cylinders of the hydraulic system are mounted directly on the working body or on the units of the working equipment. The working cavities of the power cylinders are connected to the junction boxes at the bend points by high-pressure rubber hoses, and in straight sections - by metal oil lines.
1. Hydraulic pump NPA-64
The hydraulic equipment system of the E-153 excavator includes two NPA-64 axial plunger pumps. To drive the pumps on the tractor, a gear reducer is installed with a drive from the tractor's gearbox. The gearbox engaging mechanism allows you to simultaneously turn on or off both pumps or turn on one pump.
The pump installed on the first stage of the reducer has 665 shaft rpm, the other pump (left) receives the drive from the second stage of the reducer and reaches 1500 rpm. Due to the fact that the knives have a different number of revolutions, their performance is not the same. The left pump delivers 96 l / min; right - 42.5 l / min. The maximum pressure to which the pump is adjusted is 70 75 kg / cm2.
The hydraulic system is filled with spindle oil AU GOST 1642-50 for operation at an ambient temperature of + 40 ° C; at an ambient temperature of + 5 to -40 ° C, oil can be used in accordance with GOST 982-53 and at temperatures from -25 to + 40 ° C - spindle 2 GOST 1707-51.
In fig. 2 presented general arrangement pump NPA-64. The drive shaft is mounted in the drive shaft housing on three ball bearings. The asymmetrical plunger pump housing is bolted to the right side of the drive shaft housing. The pump housing is closed and sealed with a cover. The spline end of the drive shaft is connected to the gearbox coupling, and the inner end is connected to a flange in which the eight ball heads of the connecting rods are rolled. For this, seven special bases are installed in the flange for each ball head of the connecting rod. The second ends of the connecting rods are rolled into plungers with ball heads. Plungers have their own block of seven cylinders. The block sits on a bearing support and is pressed tightly against the polished surface of the distributor by the force of the spring. In turn, the cylinder block distributor is pressed against the cover. Rotation from the drive shaft to the cylinder block is transmitted by the propeller shaft.
Rice. 2. Pump NPA-64
The cylinder block in relation to the drive shaft housing is inclined at an angle of 30 °, therefore, when the flange rotates, the rolled connecting rod heads, following along with the flanges, will give the plungers a reciprocating motion. The stroke of the plungers depends on the tilt angle of the cylinder block. With an increase in the angle of inclination, the active stroke of the plungers increases. In this case, the tilt angle of the cylinder block remains constant, therefore, the stroke of the plungers in each cylinder will also be constant.
The pump works as follows. With a full revolution of the drive shaft flange, each plunger makes two strokes. The flange, and therefore the cylinder block, rotates clockwise. The plunger that is currently at the bottom will rise with the cylinder block up. Since the flange and the cylinder block rotate in different planes, the plunger, connected by the ball head of the connecting rod to the flange, will be pulled out of the cylinder. A vacuum is created behind the piston; the resulting volume is filled with oil by the stroke of the plunger through a channel connected to the suction cavity of the pump. When the ball head of the connecting rod of the plunger in question reaches the upper extreme position (TDC, Fig. 2), the suction stroke of the plunger in question ends.
The suction period runs throughout the alignment of the channel with the channels. When the ball head of the connecting rod moves in the direction of rotation from TDC down, the plunger makes a discharge stroke. In this case, the sucked oil is squeezed out of the cylinder through the channel into the channels of the delivery line of the system.
The other six plungers of the pump do the same work.
Oil that has passed from the working chambers of the pump through the gaps between the plungers and the cylinders is drained into the oil tank through the drain hole.
Sealing of the pump cavity from leaks along the plane of the body joint, between the body and the cover, and also between the body and the flange is achieved by installing O-ring rubber seals. The flange-mounted drive shaft is sealed with a lip seal.
2. Pump safety valves
The maximum pressure in the system within 75 kg / cm2 is maintained by safety valves. Each pump has its own valve, which is installed on the pump body.
In fig. 3 shows the arrangement of the left pump safety valve. In the vertical bore of the body, a saddle is installed, which, with the help of a plug, is firmly pressed at the bottom against the shoulder of the vertical bore. On the inner wall there is an annular groove and a calibrated radial bore for the passage of the injection oil from the cavity. A valve is installed in the seat, which is pressed tightly against the conical surface of the seat by a spring. The tightening of the spring can be changed by turning the adjusting bolt in the plug. The pressure from the adjusting bolt to the spring is transmitted through the stem. When the valve is tightly seated, the suction and discharge cavities are decoupled. In this case, the oil coming from the tank through the channel will only pass to the suction cavity of the pump, and the oil pumped by the pump through the channel enters the working cavities of the power cylinders.
Rice. 3. Left pump safety valve
When the pressure in the discharge cavity rises and is more than 75 kg / cm2, the oil from the channel will pass into the annular groove of the seat and, overcoming the force of the spring, will lift the valve up. Through the formed annular gap between the valve and the seat, excess oil will pass into the suction cavity (channel 2), as a result of which the pressure in the discharge chamber will decrease to the value set by the valve spring 10.
The principle of operation of the safety valve of the right pump is similar to the case considered and differs in design by a slight change in the housing, which caused a corresponding change in the connection of the suction and discharge lines to the pump.
To maintain normal operation of the hydraulic system of the excavator, it is required to check and, if necessary, adjust the safety valve at least after 100 hours of operation.
To check and adjust the valve, a special tool is included in the tool kit, with which the adjustment is made as follows. First of all, you must turn off both pumps, then unscrew the plug from the valve body and unfold the fitting instead. Connect a high pressure gauge to the pump discharge chamber through a tube and a vibration damper. Switch on the pumps and one of the power cylinders. It is recommended to turn on the power cylinder of the boom when checking the safety valve of the left pump, and when checking the safety valve of the right cylinder, turn on the cylinder of the bulldozer.
If the pressure gauge does not show normal pressure (70-75 kg / cm2), it is necessary to adjust the pump, adhering to the following order. Remove the seal, loosen the lock nut and turn the adjusting screw 3 in the desired direction. If the pressure gauge readings are too low, tighten the screw, and if the pressure is too high, loosen it. Hold the boom or bulldozer control levers in the engaged position for no more than one minute while adjusting the relief valve. After making the adjustment, turn off the pumps, remove the adjusting device, replace the plug and seal the adjusting screw.
Rice. 4. Tool for adjusting the safety valve
3. Maintenance of the NPA-64 pump
The pump runs flawlessly if the following conditions are met:
1. Fill the system with washed oil.
2. Set the oil pressure in the system within 70-75 kg / cm2.
3. Check daily the tightness of the connection along the joint planes of the pump casings. Oil seepage is not allowed.
4. Avoid the presence of water in the intercostal cavities of the pump casing during the cold season.
4. Design and operation junction boxes
The presence of two junction boxes and two high pressure pumps in the system made it possible to create two independent hydraulic circuits, which have one common unit - a working fluid tank with oil filters.
Junction boxes are the main components in the hydraulic control mechanism; their purpose is to direct hydraulic flow with high pressure to the working chambers of the cylinder and at the same time to remove the used oil from the opposite chambers of the cylinders into the tank.
As noted above, two boxes are installed in the hydraulic system of the excavator: the smaller one is installed on the left side in the direction of the tractor and the larger one on the right side. The power cylinders of the dozer blade, the bucket and the handle cylinder are connected to the smaller box, and the power cylinders of the supports, the arms of the swing mechanism are connected to the large box. Small and large junction boxes differ from each other only by the presence of a shunt spool, which is installed on a large box and has the purpose of connecting the working cavities of the power cylinder of the boom to each other and to the drain line when it is required to obtain a quick lowering of the boom. The rest of the boxes are similar in structure and operation to each other.
In fig. 5 shows the arrangement of a small junction box.
The body of the box is cast iron, in the vertical bores of which a choke with a spool is installed in pairs. Each pair of choke - spool is rigidly connected to each other by steel rods, which are connected to the control levers through additional rods and levers. At the inner end of the choke, a special device is fixed, with the help of which the choke-valve pair is set to the neutral position. Such a device is called a nullsetter. The zero-setting device is simple and consists of washers, an upper bushing, a spring, a lower bushing, a nut and a locknut screwed onto the threaded part of the throttle. After assembling the zero-set, it is necessary to check the stroke of the throttle-spool pair.
The vertical bores, in which the throttle-spool pairs go, are closed from above with covers with lip seals, and from the bottom - with covers with special sealing rings. The free spaces above the throttle and spool, as well as under the spool chokes during operation are filled with oil that has seeped through the gaps between the body and the choke spool. The upper and lower cavities of the throttle and the spool are interconnected by means of an axial channel in the spool and special horizontal channels in the box body. The oil in these cavities is discharged through a drain pipe into the tank. In the event of a clogged drainage tube, the oil drain stops, which is detected immediately after the spontaneous activation of the spools appears.
In the small junction box, in addition to three pairs of throttle - spool, there is a speed regulator, which, when one of the two pairs located on the left side of it is operating, ensures that the oil is drained off, and when the pairs are in the neutral position, it allows the oil to pass to the drain ... When the speed controller works together with the throttle, a smooth stroke of the power cylinder rods is ensured. The above will be true if the speed controller is adjusted accordingly. The regulation of the speed regulator will be discussed a little later.
Rice. 5. Small junction box
In the third pair, the throttle-spool valve, which is located on the right side of the speed regulator (in the small and large boxes), the throttle has a slightly different device from the throttles located on the left side of the speed regulator. The indicated constructive change of the chokes in the third pair is due to the need to shut off the drain line at the moment when the choke-spool pair, located after the speed regulator, comes into operation.
Using the example of a large junction box device, we will get acquainted with the features of the operation of its nodes. The direction of the oil flow in the channels of the box depends on the position of the throttle-spool pair. In the process of work, six positions are possible.
First position. All pairs are in neutral. The oil supplied by the pump passes in the box through the upper channel A into the lower cavity of the speed regulator B and, overcoming the resistance of the speed regulator spring, will raise the regulator spool up. Through the formed annular gap 1, the oil will pass into cavities c and d and through the lower channel e it will merge into the tank.
Second position. The left throttle-spool pair, located before the speed regulator, is lifted up from the neutral position. This position corresponds to the operation of the power cylinders of the supports. The oil coming from the pump from channel A through the gap formed by the throttle will pass into cavity K and through the channels will enter cavity m above the speed control spool, after which the spool will firmly sit down and block the drain line. Oil from cavity K will go through a vertical channel into cavity B and then through pipelines to the working cavity of the power cylinder. From another cavity of the cylinder, oil will be displaced into the cavity n of the box and through channel e it will be drained into the tank.
Rice. 6a. Box operation diagram (neutral position)
Rice. 6b. The power cylinders of the supports are working
Rice. 6c. The power cylinders of the supports are working
Rice. 6d. The power cylinder is working
Third position. The left throttle-spool pair, located to the left of the speed regulator, is lowered down from the neutral position. This position of the pair also corresponds to a certain mode of operation of the power cylinders of the supports. Oil from the pump enters channel A, then into cavity K and through channels into cavity w above the speed regulator spool. The spool will close the oil drain through cavities c and e. The pumped oil from cavity K will now flow not into cavity b, as it was in the previous case, but into cavity p. Oil from the drain cylinder will be displaced into cavity b, and then into channel e and into the oil tank.
Fourth position. The pairs on the left side (upstream of the speed control) are set to neutral and the couple downstream of the speed control is in the up position.
In this case, the oil from the pump will flow through channel A into cavity B under the spool of the speed regulator and, lifting the spool up, it will pass through the formed slot 1 into cavity C; then through the vertical channel it will enter the cavity and through the oil line into the working cavity of the power cylinder. From the opposite cavity of the power cylinder, oil will be displaced into cavity 3 and through channel e it will go to drain into the tank.
Fifth position. The throttle-spool pair downstream of the speed regulator is lowered. In this case, the throttle, as in the previous case, blocked the drain line with the only difference that the cavity s began to communicate with the discharge line, and the cavity w with the drain line.
Sixth position. The shunt valve is included in the work. When the spool is lowered, the oil flow from the pump flows through the box in the same way as it did in the neutral position of steam.
In this case, cavities x and w are connected by oil lines to the planes of the power cylinder of the boom, and the lowered spool, in addition, allowed these cavities to be simultaneously connected to the drain line e. and the mounted implement is quickly lowered.
Rice. 6d. The power cylinder is working
Rice. 6f. Shunt spool in operation
5. Speed controller
In the neutral position, the throttle-spool pairs oil goes to drain through cavity B (Fig. 6 a). At the same time, the pump does not develop high pressure, since the resistance to oil passage is small and depends on the combination of channels, the stiffness of the regulator spring and the resistance of the oil filters. Thus, with the neutral position of all paos, the throttle - spool valve, the pump practically runs idle, and the spool of the speed regulator is in a raised state and is balanced in a certain position by the pressure of oil from below from cavity B and from above by a spring. The pressure drop between cavity B and C is within 3 kg / cm2.
During the movement of one of the throttle-spool pairs from the neutral position up or down (to the operating position), oil from cavity A will pass into cavity C and through the slot to drain into channel e. The rest of the oil supplied by the pump will enter the working cavity of the power cylinder and into cavity m above the speed controller spool. Depending on the load on the rod of the power cylinder in cavities m and B, the value of oil pressure will change accordingly. Under the action of the force of the regulator spring and oil pressure, the regulator spool will move down and take some new position; moreover, the size of the passage section of the slot will decrease. With a decrease in the cross-section of the slot, the amount of liquid going to the drain will also decrease. Simultaneously with the change in the size of the gap, the value of the pressure drop between the cavity B and C will also change, and with the change in the value of the differential pressure, the full equilibrium position of the speed regulator spool will appear. This equilibrium will come when the pressure of the spool spring and oil in cavity m will be equal to the oil pressure in cavity B. With a change in the load on the power cylinder rod, the oil pressure in cavities m and B will change, and this, in turn, will cause the regulator spool to be installed in new equilibrium position.
Rice. 7. Speed controller
Since the bearing surfaces of the speed regulator spool are the same from above and from below, a change in the load on the rod of the power cylinder will not affect the value of the pressure drop in the gap between cavities B and C.
This value of the pressure drop will depend only on the force of the spool spring, which means that the speed of movement of the bayonet in the power cylinder will practically remain constant and will not depend on the load.
In order for the regulator spring to provide a pressure difference between cavities B and C within 3 kg / cm2, it must be set to this pressure during assembly. In the conditions of the plant, this adjustment is made at a special stand. In the field, checking the speed regulator adjustment is carried out in the same way as previously recommended when adjusting the safety valves using pressure gauges.
To do this, you need to do the following:
1. Install a pressure gauge to the safety valve on the pump that supplies oil to the box of the speed regulator being tested and observe the pressure gauge readings when the pumps are running.
2. Unscrew the speed regulator housing from the control box housing, remove the spool and spring, and then reinstall the housing with the adjusting screw in place in the junction box.
3. Start the pumps, give the engine a normal speed and observe the pressure gauge. The first reading of the manometer should be 3-3.5 kg / cm2 more than the reading in the second case.
In order to adjust the valve, the spool spring must be tightened or lowered with the adjusting screw. After the final adjustment, the screw is fixed and sealed with a nut.
6. Installation of a pair of choke - spool
The initial setting of the throttle-spool pair to the neutral position is done at the factory. During operation, the box has to be disassembled and reassembled. As a rule, disassembly is carried out each time due to failure of the seals or due to the breakage of the zero set spring. Disassemble the junction boxes in a clean room by a qualified mechanic. When disassembling, put the removed parts in a clean container filled with gasoline. After replacing the worn out parts, proceed with the assembly, paying particular attention to the correct setting of the throttle and spool washers, as this ensures the exact setting of the throttle-spool pairs in the neutral position during the operation of the junction boxes.
Rice. 8. Scheme for selecting the thickness of the washer for the throttle
The washer is placed on the spool, its thickness should be no more than 0.5 mm.
If necessary, replace the washer (under the throttle) with a new one, you need to know its thickness. The manufacturer recommends determining the thickness of the washer by measuring and counting as shown in Fig. 8. This method of counting is due to the fact that in the process of making holes in the housing of the junction box, spools and chokes, some deviations in dimensions may be allowed.
After assembling the junction box, connect the rods of the pairs with the control levers.
The correctness of the assembly of the throttle-spool pair can be checked as follows: disconnect the oil lines from the fittings of the tested pair. Start the pumps in operation and smoothly move the corresponding control lever towards you until oil appears from the hole under the lower connection. When oil appears, stop the handle and measure how much the spool came out of the box body. After that, move the control lever away from you until oil appears from the hole under the upper fitting. When oil appears, stop the lever and measure how much the valve has moved down. When properly assembled, the measurements should have the same reading. If the readings of the travel measurements are not the same, it is necessary to put a washer under the rod of such a thickness that it is equal to half the difference between the values of the spool travel up and down from the fixed neutral position.
Junction boxes work reliably for a long time if they are kept clean at all times, check the fastening of bolted connections daily, replace worn seals in a timely manner, and systematically check and adjust the speed governor spring.
Do not disassemble the junction box without a justified need, as this causes its premature failure.
Single-acting cylinders are mounted on the column rotation mechanism. All cylinders of the E-153 excavator are not interchangeable with the power cylinders of the distributing-aggregate system of tractors and have a different device from them.
Rice. 9. Boom cylinder
The boom cylinder rod is hollow, the guide surface of the rod is chrome plated. The rods of the power cylinders of the bulldozer supports and blade are all-metal. A connecting ear is welded to the stem from the outer end, and a shank is welded to the inner end, on which a cone, a piston, two stops, a cuff are mounted, and everything is fixed with a nut. The cone at the exit of the piston from the cylinder in the extreme position abuts against the stop ring, creates a damper, as a result of which a softened piston impact at the end of the rod stroke is achieved.
The piston of the cylinder is stepped. Cuffs are installed in the stepped grooves on both sides of the piston. An O-ring is placed in the inner annular bore of the piston, which prevents oil from flowing along the rod from one cylinder cavity to another. The end of the stem shank is made on a cone, which, when entering the cover hole, creates a damper that softens the piston shock at the end of the stroke at the extreme left position.
The rear covers of the power cylinders of the swing mechanism have axial and radial drills. With the help of these holes, through a special connecting tube, the piston cavities of the cylinders are connected to each other and to the atmosphere. To prevent dust from entering the cylinder cavities, a breather is installed in the connecting pipe.
The front tires of all power cylinders, except for the bulldozer, have the same structure. For the passage of the stem, the cover has a hole into which a bronze bushing is pressed to guide the movement of the stem. Inside each cover is an O-ring, secured by a retaining ring, and a stop ring. A washer and a wiper ^ / are installed from the end of the front cover and tightened with a union nut, which is fixed on the top cover with a locknut.
Due to the peculiarities of installing the power cylinder of the bulldozer blade on the machine, its attachment point from the rear cover was moved to the traverse, for the installation of which, in the middle part, a thread was made on the power cylinder pipe. The traverse is screwed onto the cylinder pipe in such a way that the distance from the traverse axis to the center of the traverse rod hole should be 395 mm. Then the traverse is fixed with a lock nut.
During operation, the power cylinders can be partially and completely disassembled. Full disassembly is carried out during repairs, and partial disassembly when changing seals.
Three types of seals are used in the power cylinders of the E-153 excavator:
a) wipers are installed at the outlet of the rod from the cylinder. Their purpose is to clean the chrome-plated surface of the rod from dirt at the moment when the rod is retracted into the cylinder. This eliminates the possibility of oil contamination in the system;
b) cuffs are installed on the piston and in the inner groove of the upper cylinder cover. They are intended to create a reliable seal of moving joints: a piston with a cylinder mirror and a rod with a bronze bushing of the upper cover;
c) 0-shaped seals are installed in the inner annular grooves of the upper and lower covers to seal the cylinder with the covers, in the inner annular groove of the piston to seal the rod-to-piston connection.
Most often, the first two types of seals fail; less often - the third type of seals. Piston seals wear is detected simply: the loaded rod moves slowly, and in the inoperative position, spontaneous shrinkage is observed. This happens as a result of the oil flowing from one cavity to another. Wiper wear is detected by the abundant leakage of oil between the stem and the cap. Wiper wear leads, as a rule, to contamination of the oil in the system, which accelerates the wear of precision pump pairs, prematurely destroys a pair of junction boxes, disrupts the operation of safety valves and speed controllers.
Disassembly and assembly of power cylinders when replacing worn-out seals with new ones should be carried out in a specially equipped room. All parts must be thoroughly rinsed in clean gasoline before assembly.
When assembling the power cylinders, pay special attention to the safety of the O-shaped seals installed in the inner annular grooves of the covers and the piston. Before assembly, they must be well filled so that they are not pinched between the sharp edges of the annular grooves and the ends of the cylinder tube and the rod tip.
When changing the wiper, piston and rod seals, be sure to remove the top cover. When assembling the cylinders, it must be remembered that for the power cylinders of the turning mechanism, the front covers of the right and left cylinders are installed differently. For the left cylinder, the front cover is rotated relative to the rear by 75 ° clockwise and is fixed in this position with a lock nut; for the right cylinder, the front cover must be rotated relative to the rear by 75 ° counterclockwise.
8. Running in the excavator hydraulic system at idle speed
Disengage the tractor clutch and engage the oil pump mechanism. Set the engine to an average speed of 1100-1200 rpm and check the reliability of all seals in the hydraulic system. Check the installation of the column rotation stops and release the supports. Operate the control levers to check the operation of the boom by raising and lowering it several times. Then, in the same way, check the operation of the power cylinders of the arm, bucket and column rotation mechanism. Turn the seat and check the operation of the power cylinder of the bulldozer blade from the second control panel.
Under normal operating conditions, the rods of the Power Cylinders should move smoothly at a uniform speed. The rotation of the column to the right and left should be smooth. The control levers must be securely locked in neutral. Simultaneously with checking the components of the hydraulic system, check the operation of the articulated joints of the working bodies of the excavator (bucket, bulldozer). Check the backlash of the taper roller bearings of the steering column if adjustment is necessary. The oil temperature in the tank during hydraulic break-in should not exceed 50 ° C.
Category: - Tractor hydraulic equipment
